Where to apply
Because temperatures do not stay below 50° F long enough during the winter in all parts of Illinois, fall N application should not be done south of a line roughly parallel to Route 16. In areas near this boundary, evaluate soil characteristics to determine whether fall application is appropriate, he said.
Soils with high potential for nitrate leaching in the fall or early spring (sandy soils or those with excessive drainage) should not receive fall N applications. Also, regardless of location in the state, growers should not apply nitrogen in the fall to soils with high potential for nitrate leaching or soils that are very poorly drained.
Application of manure and other organic N sources should be done as far as possible from environmentally sensitive areas, such as steep slopes and bodies of water. If the application cannot be accomplished in late fall, do not apply on frozen soils in the winter.